I have tried to derive a formula from that table, but it seems completely arbitrary. The gap between some levels is much bigger or smaller than others, as a linear or quadratic function it makes no sense.

Imagine a world where the first-time D&D player rolls stats, picks a race, picks a class, picks an alignment, and buys gear to create a character. Imagine if an experienced player, maybe the person helping our theoretical player learn the ropes, could also make a character by rolling ability scores and picking a race, class, feat, skills, class features, spells or powers, and so on. Those two players used different paths to build characters, but the system design allows them to play at the same table. -Mearl

"It is a general popular error to suppose the loudest complainers for the publick to be the most anxious for its welfare." - Edmund Burke